Moura Cesar A A, Johnson Clayton, Baker Samuel R, Holtkamp Derald J, Wang Chong, Linhares Daniel C L
1Veterinary Diagnostic and Production Animal Medicine Department, Iowa State University, 1809 S Riverside Dr, Ames, Iowa 50011 USA.
Carthage Veterinary Services, Inc, 303 North 2nd Street, 62321 Carthage, IL USA.
Porcine Health Manag. 2019 Jun 11;5:13. doi: 10.1186/s40813-019-0120-2. eCollection 2019.
To mitigate production impact of porcine reproductive and respiratory syndrome (PRRS) virus outbreaks, it has been common to preventively vaccinate swine breeding herds using PRRS modified live virus (MLV) vaccine. However, attenuated PRRS virus (PRRSv) may result negative impact on farm productivity. The objective of this study was to measure the immediate impact of PRRS type 2 MLV vaccine on breeding herd performance under field conditions. Eight PRRS-stable farms routinely mass vaccinating females with commercial PRRS MLV vaccines were enrolled on study. Vaccination dates were collected and weekly changes in abortions, neonatal losses, pre-weaning mortality, pigs weaned per sow, and wean-to-first-service interval were assessed for up to 6 weeks after each vaccination. A 6-week period prior to each vaccination was established as baseline. Statistical process control (SPC) analysis was conducted to detect significant productivity decreases after MLV interventions, on each farm, and a mixed regression model was used, at the aggregated data level, to assess the productivity change 6 weeks after PRRS MLV vaccinations, compared to baseline.
Out of 65 herd-MLV vaccinations, SPC analysis detected increase on abortions 4 times (6.1%), on neonatal losses 7 times (10.7%), on pre-weaning mortality 2 times (3%), on wean-to-first-service interval 2 times (3%), and no change in total pigs weaned. On aggregated data analysis, there was no significant change in abortion rate, neonatal losses, number of pigs weaned per sow, and wean-to-first-service interval. However, there was an increase of 0.26% of pre-weaning mortality 2 weeks after vaccination compared to the baseline.
Under study conditions, individual PRRS-stable sow farms had experienced transient, and numerically small changes in productivity following PRRS type 2 MLV vaccination. There was a small increase of pre-weaning mortality 2 weeks after vaccination, but no evidence of significant production impact at aggregated data analysis for abortion rate, neonatal losses, pigs weaned per sow and wean-to-first-service interval.
为减轻猪繁殖与呼吸综合征（PRRS）病毒爆发对生产的影响，使用PRRS弱毒活疫苗（MLV）对种猪群进行预防性接种已很常见。然而，减毒的PRRS病毒（PRRSv）可能会对猪场生产力产生负面影响。本研究的目的是在田间条件下测量2型PRRS MLV疫苗对种猪群生产性能的直接影响。八个PRRS稳定的猪场参与了本研究，这些猪场常规使用商业PRRS MLV疫苗对母猪进行大规模接种。收集了疫苗接种日期，并在每次接种后长达6周的时间内评估流产、新生仔猪损失、断奶前死亡率、每头母猪断奶仔猪数以及断奶至首次配种间隔的每周变化。每次接种前的6周时间被设定为基线。进行了统计过程控制（SPC）分析，以检测每个猪场在MLV干预后生产力的显著下降，并在汇总数据层面使用混合回归模型，评估与基线相比，PRRS MLV疫苗接种6周后的生产力变化。
在65次猪群-MLV疫苗接种中，SPC分析检测到流产增加4次（6.1%），新生仔猪损失增加7次（10.7%），断奶前死亡率增加2次（3%），断奶至首次配种间隔增加2次（3%），断奶仔猪总数无变化。在汇总数据分析中，流产率、新生仔猪损失、每头母猪断奶仔猪数和断奶至首次配种间隔均无显著变化。然而，与基线相比，接种疫苗2周后断奶前死亡率增加了0.26%。
在研究条件下，个体PRRS稳定的母猪场在接种2型PRRS MLV疫苗后经历了短暂的、数值上较小的生产力变化。接种疫苗2周后断奶前死亡率略有增加，但在汇总数据分析中，没有证据表明流产率、新生仔猪损失、每头母猪断奶仔猪数和断奶至首次配种间隔有显著生产影响。
